44 research outputs found
Strategies and policies to reach a land-degradation neutral world
Despite the difficulties in quantifying the extent and
degree of land degradation or restoration, evidence
shows that continued land degradation will be an
impediment to meeting several SDGs. The United
Nations states that it aims for land degradation
neutrality (LDN) which in 2015 became firmly
established as an agreed-upon objective in the realm
of international environmental politics. First, as part
of the SDGs whose Target 15.3 calls to “combat
desertification, restore degraded land and soil,
including land affected by desertification, drought
and floods, and strive to achieve a land degradationneutral
world” by 2030 (UNGA, 2015). The Conference
of Parties (COP) of the United Nations Convention to
Combat Desertification (UNCCD) took the decision
to align the implementation of the Convention with
SDG 15.3 and invited its Parties to set voluntary LDN
targets (UNCCD, 2015). From that point onwards,
the key question is how to implement these global
aspirations at the national level and what is needed to
operationalize the LDN concept and translate it into
concrete strategies to meet LDN at scale..
Ultra-thin polymer foil cryogenic window for antiproton deceleration and storage
We present the design and characterization of a cryogenic window based on an ultra-thin aluminized biaxially oriented polyethylene terephthalate foil at T < 10 K, which can withstand a pressure difference larger than 1 bar at a leak rate < 1 × 1 0 − 9 mbar l/s. Its thickness of ∼1.7 μm makes it transparent to various types of particles over a broad energy range. To optimize the transfer of 100 keV antiprotons through the window, we tested the degrading properties of different aluminum coated polymer foils of thicknesses between 900 and 2160 nm, concluding that 1760 nm foil decelerates antiprotons to an average energy of 5 keV. We have also explicitly studied the permeation as a function of coating thickness and temperature and have performed extensive thermal and mechanical endurance and stress tests. Our final design integrated into the experiment has an effective open surface consisting of seven holes with a diameter of 1 mm and will transmit up to 2.5% of the injected 100 keV antiproton beam delivered by the Antiproton Decelerator and Extra Low ENergy Antiproton ring facility of CERN
A 16 Parts per Trillion Comparison of the Antiproton-to-Proton q/m Ratios
The Standard Model (SM) of particle physics is both incredibly successful and
glaringly incomplete. Among the questions left open is the striking imbalance
of matter and antimatter in the observable universe which inspires experiments
to compare the fundamental properties of matter/antimatter conjugates with high
precision. Our experiments deal with direct investigations of the fundamental
properties of protons and antiprotons, performing spectroscopy in advanced
cryogenic Penning-trap systems. For instance, we compared the proton/antiproton
magnetic moments with 1.5 ppb fractional precision, which improved upon
previous best measurements by a factor of >3000. Here we report on a new
comparison of the proton/antiproton charge-to-mass ratios with a fractional
uncertainty of 16ppt. Our result is based on the combination of four
independent long term studies, recorded in a total time span of 1.5 years. We
use different measurement methods and experimental setups incorporating
different systematic effects. The final result,
= ,
is consistent with the fundamental charge-parity-time (CPT) reversal
invariance, and improves the precision of our previous best measurement by a
factor of 4.3. The measurement tests the SM at an energy scale of
GeV (CL 0.68), and improves 10 coefficients of the
Standard Model Extension (SME). Our cyclotron-clock-study also constrains
hypothetical interactions mediating violations of the clock weak equivalence
principle (WEP) for antimatter to a level of , and enables the first differential test of the WEP
using antiprotons \cite{hughes1991constraints}. From this interpretation we
constrain the differential WEP-violating coefficient to
Ultra thin polymer foil cryogenic window for antiproton deceleration and storage
We present the design and characterisation of a cryogenic window based on an
ultra-thin aluminised PET foil at T < 10K, which can withstand a pressure
difference larger than 1bar at a leak rate < mbar l/s.
Its thickness of approximately 1.7 m makes it transparent to various types
of particles over a broad energy range. To optimise the transfer of 100keV
antiprotons through the window, we tested the degrading properties of different
aluminium coated PET foils of thicknesses between 900nm and 2160nm, concluding
that 1760nm foil decelerates antiprotons to an average energy of 5 keV. We have
also explicitly studied the permeation as a function of coating thickness and
temperature, and have performed extensive thermal and mechanical endurance and
stress tests. Our final design integrated into the experiment has an effective
open surface consisting of 7 holes with 1 mm diameter and will transmit up to
2.5% of the injected 100keV antiproton beam delivered by the AD/ELENA-facility
of CERN
Land in balance: the scientific conceptual framework for land degradation neutrality
The health and productivity of global land resources are declining, while demand for those resources is increasing. The aim of land degradation neutrality (LDN) is to maintain or enhance land-based natural capital and its associated ecosystem services. The Scientific Conceptual Framework for Land Degradation Neutrality has been developed to provide a scientific approach to planning, implementing and monitoring LDN. The Science-Policy Interface of the United Nations Convention to Combat Desertification (UNCCD) led the development of the conceptual framework, drawing in expertise from a diverse range of disciplines. The LDN conceptual framework focuses on the supporting processes required to deliver LDN, including biophysical and socio-economic aspects, and their interactions. Neutrality implies no net loss of the land-based natural capital relative to a reference state, or baseline. Planning for neutrality involves projecting the likely cumulative impacts of land use and land management decisions, then counterbalancing anticipated losses with measures to achieve equivalent gains. Counterbalancing should occur only within individual land types, distinguished by land potential, to ensure “like for like” exchanges. Actions to achieve LDN include sustainable land management (SLM) practices that avoid or reduce degradation, coupled with efforts to reverse degradation through restoration or rehabilitation of degraded land. The response hierarchy of Avoid > Reduce > Reverse land degradation articulates the priorities in planning LDN interventions. The implementation of LDN is managed at the landscape level through integrated land use planning, while achievement is assessed at national level. Monitoring LDN status involves quantifying the balance between the area of gains (significant positive changes in LDN indicators) and area of losses (significant negative changes in LDN indicators), within each land type across the landscape. The LDN indicators (and associated metrics) are land cover (physical land cover class), land productivity (net primary productivity, NPP) and carbon stocks (soil organic carbon (SOC) stocks). The LDN conceptual framework comprises five modules: A: Vision of LDN describes the intended outcome of LDN; B: Frame of Reference clarifies the LDN baseline; C: Mechanism for Neutrality explains the counterbalancing mechanism; D: Achieving Neutrality presents the theory of change (logic model) articulating the impact pathway; and E: Monitoring Neutrality presents the LDN indicators. Principles that govern application of the framework provide flexibility while reducing risk of unintended outcomes.Annette L. Cowie, Barron J. Orr, Victor M. Castillo Sanchez, Pamela Chasek, Neville D. Crossman, Alexander Erlewein, Geertrui Louwagie, Martine Maron, Graciela I. Metternicht, Sara Minelli, Anna E. Tengberg, Sven Walter, Shelley Welto
BASE-STEP: A transportable antiproton reservoir for fundamental interaction studies
Currently, the only worldwide source of low-energy antiprotons is the
AD/ELENA facility located at CERN. To date, all precision measurements on
single antiprotons have been conducted at this facility and provide stringent
tests of the fundamental interactions and their symmetries. However, the
magnetic field fluctuations from the facility operation limit the precision of
upcoming measurements. To overcome this limitation, we have designed the
transportable antiproton trap system BASE-STEP to relocate antiprotons to
laboratories with a calm magnetic environment. We anticipate that the
transportable antiproton trap will facilitate enhanced tests of CPT invariance
with antiprotons, and provide new experimental possibilities of using
transported antiprotons and other accelerator-produced exotic ions. We present
here the technical design of the transportable trap system. This includes the
transportable superconducting magnet, the cryogenic inlay consisting of the
trap stack and the detection systems, and the differential pumping section to
suppress the residual gas flow into the cryogenic trap chamber.Comment: To be submitted to Rev. Sci. Instrument
Trap-integrated fluorescence detection based on silicon photomultipliers in a cryogenic Penning trap
We present a fluorescence-detection system for laser-cooled 9Be+ ions based
on silicon photomultipliers (SiPM) operated at 4 K and integrated into our
cryogenic 1.9 T multi-Penning-trap system. Our approach enables fluorescence
detection in a hermetically-sealed cryogenic Penning-trap chamber with limited
optical access, where state-of-the-art detection using a telescope and
photomultipliers at room temperature would be extremely difficult. We
characterize the properties of the SiPM in a cryocooler at 4 K, where we
measure a dark count rate below 1/s and a detection efficiency of 2.5(3) %. We
further discuss the design of our cryogenic fluorescence-detection trap, and
analyze the performance of our detection system by fluorescence spectroscopy of
9Be+ ion clouds during several runs of our experiment.Comment: 12 pages, 11 figure
Capture of an external anion beam into a linear Paul trap
We describe a linear Paul trap and high-voltage platform specifically designed for the trapping of a large and pure sample of anions from an external keV-energy beam. Capture and confinement in a static configuration of DC potentials was found to occur by transfer of axial to radial ion momentum due to elastic and inelastic collisions. Stability diagrams both in transmission and capture mode were recorded. The trapping efficiency was observed to be very sensitive to the axial potentials relative to the beam energy. Several 10 oxygen anions were loaded from a 2 keV primary beam and confined for several 100 s. Identification of trapped O− ions and contaminants was achieved by selective laser photodetachment
Unpacking the concept of land degradation neutrality and addressing its operation through the Rio Conventions
The world's commitment towards land degradation neutrality (LDN) became enshrined in various international agreements and decisions throughout the year 2015. The challenge now becomes one of addressing its operation, in order to achieve these new policy goals and targets by the year 2030. Advancing LDN demands attention to what the concept seeks to achieve, as well as unravelling the perspectives of the key multi-lateral environmental agreements through which progress can be made. The three Rio Conventions (the UN Convention to Combat Desertification (UNCCD), the UN Framework Convention on Climate Change (UNFCCC) and the Convention on Biological Diversity (CBD)) all play key roles in shaping the international LDN governance and implementation context. Their different but related foci create a number of challenges and opportunities for advancing LDN. In this paper we critically analyze the literature to elucidate potential challenges and opportunities in moving LDN towards implementation, considering the mandates and objectives of all three Rio Conventions. We first unpack the concept of LDN's aspirations. We highlight the importance of the definitions and terminology used, and the relationships between those definitions, terms and the actors using them, as well as their implications in framing the range of policy actions and synergies that could benefit progress towards multiple Sustainable Development Goals. We then examine the LDN pilot project spearheaded by the UNCCD to identify key lessons for LDN implementation. Synthesizing these lessons, we present a portfolio of blended interventions that seeks to address the aspirations of the UNCCD, UNFCCC and CBD in the LDN space, identifying synergistic options for national actions to move towards LDN. Overall, our analysis provides insights in advancing LDN from its current position as a policy target, towards synergetic action